KR100330711B1 - Spindle motor - Google Patents

Abstract

The present invention integrally forms a thrust in the drive shaft, and the dynamic pressure generating groove is formed on the inner circumferential surface and cover plate of the sleeve which is less affected by the frictional force with the fluid, so that better wear resistance and productivity can be exhibited. The present invention relates to a motor, and to the above object, the present invention relates to a spindle motor comprising a base plate (10), a sleeve (20), a stator assembly (30), a shaft (40), and a rotor assembly (50). The lower end portion of the 40 has a flange shape so that the thrust 41 is integrally formed, and the inner diameter surface of the sleeve 20 facing the upper surface of the thrust 41 and the lower surface of the thrust 41 are formed. To generate dynamic pressure in the axial direction to the upper surface of the cover plate 60 which seals the lower end of the oil hole 21 of the sleeve 20 facing each other. The dynamic pressure generating grooves 80 are formed to increase workability, workability, and productivity in the manufacturing process of the spindle motor, and at the same time improve the wear resistance and the characteristics of NRRO and RRO during operation, thereby extending the service life and performance of the motor. It is to improve the reliability.

Description

Spindle motor

The present invention integrally forms a thrust in the drive shaft, and the dynamic pressure generating groove is formed on the inner circumferential surface of the sleeve and the cover plate which are less affected by friction with the fluid, so that the wear resistance and productivity can be exerted. It's about a motor.

In general, a spindle motor used in a hard disk driver requires a high speed driving force and employs a hydrodynamic bearing with a lower driving load.

1 illustrates an example of a spindle motor to which a conventional hydrodynamic bearing is applied. As a constituent means of the motor, a fixing member and a shaft including a base plate 1, a sleeve 2, and a stator core assembly 3 are shown. There is a rotating member consisting of (4) and hub (5) and magnet (6).

The sleeve 2 allows the shaft 4 to be rotatably inserted so that the center thereof penetrates in the vertical direction, and the sleeve 2 allows the lower portion of the shaft 4 to have a larger inner diameter at the lower portion than the upper portion thereof. The disk-shaped thrust 7 is configured to be rotatably coupled with the shaft 4.

In particular, the lower end of the sleeve (2) is covered by the cover plate 8, the inner diameter is blocked from the outside, the cap-shaped hub (5) is openly coupled to the upper end of the shaft (4).

In the above-described structure, the oil is filled by forming a fine gap between the inner diameter surface of the sleeve 2 and the shaft 4 and the thrust 7.

In addition, on the inner diameter surface of the sleeve 2 facing each other with the shaft 4 and the oil gap G interposed therebetween, a dynamic pressure generating groove 2a is formed in the upper and lower portions as shown in FIG. It generates a fluid dynamic pressure, as shown in Figure 3 to form a dynamic pressure generating groove (7a) in the upper and lower surfaces of the thrust (7) coupled to the lower end of the shaft 4 to generate the fluid dynamic pressure in the axial direction .

At this time, the dynamic pressure generating groove 2a formed in the sleeve 2 generates dynamic pressure in the radial direction of the shaft, and the dynamic pressure generating groove 7a formed in the thrust 7 generates dynamic pressure in the axial direction.

Therefore, oil in the oil gap G is concentrated in the dynamic pressure generating groove 2a of the sleeve 2 and the dynamic pressure generating groove 7a of the thrust 7 when the shaft 4 rotates, so that the oil gap G always remains. It is to be kept uniform, thereby allowing the shaft 4 to be driven stably.

However, in the spindle motor of the related art, there are some problems in the area generating the fluid dynamic pressure.

First of all, since the thrust 7 is assembled by hot rolling on the shaft 4, not only a great precision is required to process the inner diameter of the thrust 7, but also a right angle with the shaft 4 must be perpendicular to the inner diameter. Management is very difficult.

And since the dynamic pressure generating grooves 7a formed on both sides of the thrust 7 cannot be processed concurrently in reality, they must be processed sequentially, but processing variations occur in the dynamic pressure generating grooves 7a formed by such processing.

As such, the thrust 7 requires a very difficult operation not only for self-processing but also for assembling with the shaft 4, resulting in a decrease in productivity.

Second, as the dynamic pressure generating groove 7a is formed in the thrust 7 which rotates simultaneously with the shaft 4, the wear resistance of the thrust 7 may be deteriorated by severe friction with oil when the shaft 4 rotates.

Third, since the dynamic pressure generating grooves 7a formed on the thrust 7 cannot be processed on both sides at the same time as described above, the degree of processing of the dynamic pressure generating grooves 7a formed on both sides is formed non-uniformly, especially the conventional shaft. (4) and thrust (7) are made of SUS series metal, while the sleeve (2) is made of brass or bronze material having a larger thermal expansion coefficient. Therefore, the oil gap (G) at high temperatures due to the difference in thermal expansion coefficient between the two materials ) Is excessively wide or the change is severe and there is a problem that the drive of the motor becomes unstable.

These problems eventually lead to deterioration of the motor and deteriorate the reliability of the product.

The present invention is to compensate for the above problems, the present invention is to provide a dynamic pressure generating groove for generating an axial dynamic pressure on the sleeve and cover plate facing the upper and lower surfaces of the thrust, the thrust shaft The main purpose is to improve the wear resistance of the thrust and to improve the productivity and productivity at the same time by manufacturing integrally with the.

In addition, another object of the present invention is to manufacture the sleeve as a material having a lower coefficient of thermal expansion compared to the shaft and thrust so that the oil cap can be uniformly maintained and stable driving can be performed.

1 is a side cross-sectional view showing a conventional spindle motor,

Figure 2 is a half sectional perspective view showing a sleeve of a conventional spindle motor,

3 is a perspective view illustrating a thrust of a conventional spindle motor;

4 is a side cross-sectional view of a spindle motor according to the present invention;

5 is an exploded perspective view showing an embodiment of a hydrodynamic bearing in the spindle motor according to the present invention;

Figure 6 is an exploded perspective view showing another embodiment of a hydrodynamic bearing in the spindle motor according to the present invention.

<Description of the symbols for the main parts of the drawings>

20: sleeve 40: shaft

41: thrust 60: cover plate

70: fluid dynamic pressure generating groove in the radial direction of the shaft

80: fluid dynamic pressure generating groove in the axial direction

In order to achieve the above object, the present invention provides a base plate, a sleeve coupled to the base plate, a stator assembly coupled to an outer circumferential surface of the sleeve at an upper portion of the base plate, and vertically penetrating the center of the sleeve. A shaft is rotatably inserted into the oil hole, and a magnet for generating electromagnetic force by interacting with the stator assembly to the inner circumferential surface of the outer peripheral end portion of the hub extending downwardly is integrally coupled to the shaft. In a spindle motor consisting of a rotor assembly,

The shaft is flanged to the lower end so that the thrust is integrally formed, and an inner diameter surface of the sleeve facing the upper surface of the thrust and an oil hole lower end of the sleeve facing the lower surface of the thrust are closed. The most prominent feature of the upper surface of the plate is that dynamic pressure generating grooves are formed to generate dynamic pressure in the axial direction, respectively.

Hereinafter, described in detail with reference to the accompanying drawings a preferred embodiment of the present invention.

Figure 4 is a side cross-sectional view showing a spindle motor according to the present invention, the configuration consisting of the base plate 10, the sleeve 20, the stator assembly 30, the shaft 40 and the rotor assembly 50 is conventionally Is the same as

That is, the base plate 10 is a fixing member of a flat plate, and the base plate 10 is firmly coupled to the base plate 10 by the interference fit or the adhesive by the outer peripheral surface of the lower end of the tubular sleeve 20 which vertically penetrates the center thereof.

The sleeve 20 has an oil hole vertically penetrated at the center thereof, the stator assembly 30 is coupled to an outer circumferential surface thereof, and the shaft 40 is fitted into the oil hole.

And the rotor assembly 50 consisting of a downwardly open cap-shaped hub 51 to which the magnet 52 is attached to the inner circumferential surface of the extended end extending downward of the outer end is coupled to the upper end of the shaft 40, the sleeve ( A cover plate 60 is attached to the lower end of 20) by an adhesive or the like so that the lower end of the vertically penetrated oil hole is shielded from the outside.

The spindle motor of this configuration has a shaft 40 caused by the electromagnetic force generated by the interaction between the core of the stator assembly 30 and the magnet 52 of the rotor assembly 50 when power is applied to the stator assembly 30 from the outside. And the rotor assembly 50 is rotated and driven together.

Meanwhile, in order to prevent friction with the sleeve 20 when the shaft 50 rotates, an oil gap G is formed at minute intervals between the outer diameter surface of the shaft 40 and the inner diameter surface of the sleeve 20. The oil cap G is filled with oil.

The oil filled in the oil hole (G) forms a constant hydraulic pressure while flowing in the rotational direction of the shaft 40 when the shaft 40 rotates, the shaft 40 is the radial direction and the shaft of the shaft under the influence of this hydraulic pressure It has the property to move in the direction.

Therefore, in the past, dynamic pressure generating grooves 70 were formed on at least one side of the outer diameter surface of the shaft 40 or the inner diameter surface of the sleeve 20 facing the shaft 40 so as to be strong in the radial direction of the shaft in the oil gap G. The inter fluid dynamic pressure is formed, and the oil gap G between the sleeve 20 and the shaft 40 is uniformly maintained by the fluid dynamic pressure at this time.

Dynamic pressure generating groove 70, which is formed as a means for generating a fluid dynamic pressure in the radial direction of such an axis, was formed in the outer circumferential surface of the shaft 40 in the past, but dynamic pressure is generated in the shaft 40, which is a rotating member. When the groove 70 is formed, the friction between the shaft 40 and the oil becomes severe, and the friction force acts as a rotating load, and the wear resistance of the shaft 40 is deteriorated. It is common to have a dynamic pressure generating groove 70 for generating fluid dynamic pressure in the radial direction of the shaft on the inner diameter surface of 20.

On the other hand, the thrust 41 provided as the lower end of the shaft 40 is provided as a means for generating the fluid dynamic pressure in the axial direction together with the fluid dynamic pressure in the radial direction of the shaft.

The thrust 41 is usually made of a circular plate member having a larger outer diameter than the inner diameter of the sleeve 20 into which the shaft 40 is inserted, so that the inner diameter of the sleeve 20 provided with the thrust 41 is thrust. Since the oil hole of the sleeve 20 extends larger than the outer diameter of 41, the oil hole of the sleeve 20 has a stepped shape having a larger inner diameter than the upper portion.

The thrust 41 prevents the shaft 40 from rising upward when rotated, and the upper surface of the thrust 41 and the stepped inner diameter surface of the sleeve 20 and the lower surface of the thrust 41 and the oil hole. A fluid dynamic pressure in the axial direction is generated between the upper surfaces of the cover plate 70 so that the lower end is shielded from the outside.

According to the present invention, the thrust 41 which is provided as a means for generating the fluid dynamic pressure in the axial direction is formed in a structure that is integrally manufactured with the shaft 40, as shown in FIG. 80 is characterized in that it is formed to be formed of the stepped inner diameter surface of the sleeve 20 and the upper surface of the cover plate 60 respectively opposed to the upper surface and the lower surface of the thrust (41).

In other words, the thrust 41 is formed in a structure formed integrally as a flange at the lower end of the shaft 40, and the upper oil hole 21 of the sleeve 20 facing the upper surface of the thrust 41 is opposed. At the lower end of the sleeve 20, a dynamic pressure generating groove 80 for generating fluid dynamic pressure in the axial direction is formed at a horizontal inner diameter surface which is stepped between the lower oil hole 21 having a larger inner diameter. A dynamic pressure generating groove 80 is also formed on the upper surface of the cover plate 60 which is coupled to shield the oil hole 21 from the outside in order to generate a fluid dynamic pressure in the axial direction formed on the inner diameter surface of the sleeve 20. To make it possible.

In addition, according to the present invention, the thrust 41 is formed in a structure that is integrally formed with the shaft 40 as shown in FIG. 6, and the pressure generating grooves 80 are respectively formed on the upper surface of the thrust 41 and the upper surface of the cover plate 60. It is also possible to implement a structure that allows) to be formed.

In such a configuration, the shaft 40 and the cover plate 60 are made of a stainless metal as before, but the sleeve 20 is formed of a material having a lower coefficient of thermal expansion than the shaft 40 and the cover plate 60. It is more preferable to do.

When the formation structure of the thrust 41 and the axial dynamic pressure generating groove 80 is improved, first, the shaft 40 and the thrust 41 are integrally manufactured, and the shaft and the thrust are separated as before. Compared with the production, there is an advantage that production is easier.

In addition, since the shaft 40 and the thrust 41 should be formed to be orthogonal to each other, when manufacturing them separately as in the past, it is very difficult to manage the inner diameter surface workability of the thrust coupled with the shaft, especially the squareness, but they are integrally integrated as in the present invention. This makes it easier to manage the squareness between these configurations, which can be very fast.

In addition, a dynamic pressure generating groove 80, which is formed as a means for generating dynamic pressure in the axial direction, has an inner diameter surface of the sleeve 20, which is the driven body, and an upper surface of the cover plate 60 or an upper portion of the thrust 41. When the surface and the upper surface of the cover plate 60 are formed, respectively, it is possible to provide more uniform workability and easier operation than the conventional case formed with both sides of the thrust.

It is thus possible to provide faster fabrication of the motor in accordance with the present invention.

In addition, when the dynamic pressure generating groove 80 is formed as the inner diameter surface of the sleeve 20, which is the driven body and not the driving body, and the upper surface of the cover plate 60, the frictional force with the oil is greatly reduced, thereby improving the wear resistance of the motor. There is a number.

In addition, when the sleeve 20 is provided as a material having a coefficient of thermal expansion lower than that of the shaft 40 or the cover plate 60 as described above, the sleeve 20 and the shaft at least initially driven at a high temperature when the motor is driven at high speed. Since the oil gap (G) between the 40 can no longer be opened, the rate of change of the characteristic at high temperatures is reduced, and in particular, the characteristics of the non-repeatable runout (NRRO) and the repeatable runout (RRO) in the motor can be improved. It becomes the number.

As described above, according to the present invention, a dynamic pressure generating groove 80 for generating dynamic pressure in the axial direction while manufacturing the thrust 41 integrally with the shaft 40 is provided on the upper and lower surfaces of the thrust 41, respectively. Since it is formed on the inner surface of the opposite sleeve 20 and the upper surface of the cover plate 60, respectively, there is an advantage of minimizing the frictional force with the oil when driving to improve wear resistance.

In addition, the present invention forms the sleeve 20 as a material having a lower coefficient of thermal expansion than the shaft 40, thereby reducing the rate of change in high temperature characteristics during high speed driving of the shaft 40 and the NRRO that affects the vibration and noise of the motor. There are also performance benefits that will improve the characteristics of the RRO.

Therefore, the present invention increases the workability and workability and productivity in the manufacturing process, and at the same time improves the wear resistance during operation and the characteristics of the NRRO and RRO, thereby improving the useful life of the motor and improving the reliability of the performance. Will be provided.

Claims (4)

A base plate 10, a sleeve 20 coupled to the base plate 10, a stator assembly 30 coupled to an outer circumferential surface of the sleeve 20 at an upper portion of the base plate 10, The shaft 40 is rotatably inserted into the oil hole 21 vertically penetrated to the center of the sleeve 20, and the hub 40 is integrally coupled to the shaft 40 so that the hub ( In the spindle motor comprising a rotor assembly (50) attached to the inner circumferential surface of the downwardly extending outer circumferential end of 51) and a magnet (52) generating electromagnetic force by interaction with the stator assembly (30), The shaft 40 has a lower end portion in which the thrust 41 is integrally formed in a flange shape, and has an inner diameter surface of the sleeve 20 facing the upper surface of the thrust 41 and a lower portion of the thrust 41. Spindle motor for forming dynamic pressure generating grooves 80 for generating dynamic pressure in the axial direction, respectively, on the upper surface of the cover plate 60 for sealing the lower end of the oil hole 21 of the sleeve 20 facing the surface. . The spindle motor of claim 1, wherein the sleeve is made of a material having a lower coefficient of thermal expansion than the shaft. A base plate 10, a sleeve 20 coupled to the base plate 10, a stator assembly 30 coupled to an outer circumferential surface of the sleeve 20 at an upper portion of the base plate 10, and The shaft 40 is rotatably inserted into the oil hole 21 vertically penetrated to the center of the sleeve 20, and the hub 40 is integrally coupled to the shaft 40 so that the hub ( In the spindle motor comprising a rotor assembly (50) attached to the inner circumferential surface of the downwardly extending outer circumferential end of 51) and a magnet (52) generating electromagnetic force by interaction with the stator assembly (30), An oil of the sleeve 20 is formed in the shaft 40 so that the thrust 41 is integrally formed in a flange shape at a lower end thereof and is opposed to an upper surface of the thrust 41 and a lower surface of the thrust 41. Spindle motor for forming a dynamic pressure generating groove (80) for generating dynamic pressure in the axial direction to the upper surface of the cover plate (60) for sealing the lower end of the hole (21). 4. The spindle motor of claim 3, wherein the sleeve (20) is made of a material having a lower coefficient of thermal expansion than the shaft (40).